This study will be a 3-way crossover dosing with two additional periods to determine the bioavailability of oral TMTX in patients with cancer. Trimetrexate glucoronate (TMTX) has been tested intravenously in cancer patients and has shown some activity against various tumor types. Limited studies have been conducted with oral TMTX in AIDS patients with pneumocystis carinii pneumonia and/or toxoplasmosis. Oral dosing in cancer patients will be determined based on information obtained from pharmocokinetics data collected during the study. TMTX administered with leucovorin suggests diminished toxicity. TMTX could potentially be an orally administered chemotherapy used to treat tumors which show transport-resistance to classical antifols such as methotrexate while displaying acceptable toxicity.